Before you serve Form 4A, make sure the rent figure and the evidence behind it are telling the same story. The form is much easier to stand behind when the number has been checked first.
Form 4A matters, but it does not make a weak figure stronger by itself. If the tenant asks why the rent is going up, the answer has to come from the comparables and the way the file has been put together.
That is why the checker belongs before the paid pack. It helps you test the number and the market position before those details are locked into the final notice.
Use the free tool to see whether the proposed figure is in the supportable range and whether challenge risk is already visible.
Then the paid pack becomes a cleaner follow-on step: Standard if the file is straightforward, Defence if the rent or the likely response needs more preparation.